1. Field of the Invention
The present invention relates to manipulating hydraulic pressure gradients underneath the ground surface to in turn manipulate or isolate movement of moisture through the ground, and in particular, relates to such manipulation to improve such things as barrier systems for the long-term underground passive storage of waste materials, to contain environmentally hazardous spills in the ground, or to hydraulically isolate any given unsaturated volume in the ground.
2. Problems in the Art
Modern society has created a number of environmentally dangerous materials. Significant problems exist with respect to these materials when the materials are stored above or below ground, are accidentally spilled on the ground, or need to be stored underground. Water and moisture, because of the porosity of the layers of the ground, normally tend to migrate downwardly and can then wet and subsequently move some of these hazardous products downwardly into the water table or ground water source. This can then directly affect all living things that make use of that water source.
One example of this situation is long-term underground storage of nuclear waste. If simply buried in the ground, water from rain or other sources will partially saturate the ground above the waste. Normally the pressure gradients are such that water generally moves downwards. It therefore can move down to the waste, wet the waste, and continue to move down to the water table.
One effort to deter this from happening utilizes what is called a barrier system. The barrier system basically includes a structured cover over the buried waste to attempt to divert water laterally away from the ground above the waste.
A conventional barrier system would utilize several layers constructed above the waste. Directly above the waste is normally a fine, compacted layer of soil or clay which is intended to be virtually impervious to water. Above it would be a layer of coarse material that would be used to channel water laterally. Above the coarse layer could be top soil in which plant growth might be encouraged, or simply soil that is in turn covered by some other type of materials such as riprap to further attempt to divert water away from the area of the waste.
Barriers for nuclear waste must last thousands of years to be effective. Even the best barrier systems are subject to erosion and degradation. Over time this could result in reduction in the ability of the barrier to keep water from moving to the waste.
A real need exists, therefore, for improvements in such type of barrier systems. Obviously, these systems are cheaper than creating vaults out of cement or other expensive materials requiring costly construction, and therefore are economically attractive. Their integrity against such water supply contamination, however, can be improved.
Another situation that presents problems is if a contaminant is spilled in the ground, or a material is stored on or in the ground which has components which would be detrimental to the ground water. It is difficult, if not impossible, to isolate those types of problems in a localized area or volume of the ground.
A real need therefore exists for a way to hydraulically isolate these types of problems.
It can therefore be seen that there is a real and significant need in the art for a means and method to provide solutions or improve upon the ways now used to deal with these matters.
It is therefore a primary object in the present invention to provide a means and method for hydraulically isolating any given unsaturated zone in the soil.
Another object in the present invention is to provide a means and method as above described which hydraulically isolates a given zone or area in the ground by forcing air through the area in the ground using either a passive (wind-driven) system or a forced air system. Some applications might require an initial active system followed by a long term passive system.
Another object in the present invention is to provide a means and method as above described which can be used for a variety of different situations, for a variety of different areas, zones, and locations.
A still further object in the present invention is efficient, economical, and durable.
These and other objects, features, and advantages of the present invention will become more apparent with reference to the accompanying specification and claims.